What is the name of this filter?

[John Lyons]

What filter is this?

[antonis]

I should name it "Myriam" or "Katie"..

[PRR]

What filter is this?

Bridged Tee filter. Makes a notch. When in the NFB loop, makes a bump. If you want to change Fo and Q independently, use a fancier filter.

[John Lyons]

I should name it "Myriam" or "Katie"..

I guess Tina then.

[John Lyons]

What filter is this?

Bridged Tee filter. Makes a notch. When in the NFB loop, makes a bump. If you want to change Fo and Q independently, use a fancier filter.

Ah, I was thinking T but forgot about bridged...
When I vary the 4k7 I get a Notch or a boost.
Thanks.

[antonis]

Tina

[ElectricDruid]

Funny this should come up now. I've been reading old analogue drum machine schematics this weekend, and they're full of this circuit. The Roland TR-808 service manual mentions it, for example.

In a drum machine, you set up the filter so it resonates a bit (so decent amount of Q) and then you hit it with a trigger pulse or a burst of noise. The resulting "BOooomm" sounds somewhat like a drum.

[ElectricDruid]

Bridged Tee filter. Makes a notch. When in the NFB loop, makes a bump. If you want to change Fo and Q independently, use a fancier filter.

If I wanted a bandpass like you can do with this Bridged-T design, but I wanted to be able to change the resonant frequency without messing with the Q, what would you recommend? What's next simplest?
A state variable filter would do it, but seems like overkill: three op-amps, dual pot.

[antonis]

If I wanted a bandpass like you can do with this Bridged-T design

Narrow band, of course..